1. Field of the Invention
This invention relates to an image read-out method and apparatus, which are capable of being utilized commonly in an autoradiography image detecting system, a chemiluminescence image detecting system, an electron microscope image detecting system, a radiation diffraction image detecting system, and a fluorescence image detecting system.
2. Description of the Related Art
It has been proposed to use stimulable phosphors as radiation detecting materials in radiation image diagnosing systems. Specifically, energy from radiation carrying image information of an object is stored and recorded on a stimulable phosphor, which is contained in a stimulable phosphor layer of a stimulable phosphor sheet. The stimulable phosphor layer of the stimulable phosphor sheet, on which the radiation image information has been stored, is then exposed to an electromagnetic wave acting as stimulating rays, which cause the stimulable phosphor to emit light in proportion to the amount of energy stored on the stimulable phosphor during its exposure to the radiation. The light emitted by the stimulable phosphor, upon stimulation thereof, is photoelectrically detected and converted into a digital image signal. The digital image signal is then processed and used for the reproduction of the radiation image information of the object as a visible image on a recording material.
Also, it has been proposed to use stimulable phosphors as radiation detecting materials in autoradiography image detecting systems. Specifically, a substance imparted with a radioactive label is administered to an organism, and the organism or part of a tissue of the organism is taken as a sample. The sample and a stimulable phosphor sheet provided with a stimulable phosphor layer are superposed one upon the other for a predetermined length of time, and energy from the radiation emitted by the radioactive label contained in the sample is thus stored on the stimulable phosphor contained in the stimulable phosphor layer of the stimulable phosphor sheet. The stimulable phosphor layer of the stimulable phosphor sheet, on which the radiation image information of the sample has been stored, is then exposed to an electromagnetic wave acting as stimulating rays, which cause the stimulable phosphor to emit light in proportion to the amount of energy stored on the stimulable phosphor during its exposure to the radiation. The light emitted by the stimulable phosphor, upon stimulation thereof, is photoelectrically detected and converted into a digital image signal. The digital image signal is then processed and used for the reproduction of the radiation image information of the sample as a visible image on a recording material. The autoradiography image detecting systems are disclosed in, for example, Japanese Patent Publication Nos. 1(1989)-60782, 1(1989)-60784, and 4(1992)-3952.
Further, it has been proposed to use stimulable phosphors as light detecting materials in chemiluminescence image detecting systems, the stimulable phosphors having the characteristics such that the stimulable phosphors absorb and store energy from light during exposure to the light and, when the stimulable phosphors are then stimulated by an electromagnetic wave having wavelengths falling within a specific wavelength range, the stimulable phosphors emit light in proportion to the amount of energy stored on the stimulable phosphors during the exposure of the stimulable phosphors to the light. Specifically, a biopolymer whose protein sequence, nucleic acid sequence, or the like, has been fixed is selectively labeled with a labeling substance capable of producing chemiluminescence when being brought into contact with a chemiluminescence substrate. The biopolymer having thus been selectively labeled with the labeling substance capable of producing the chemiluminescence is then brought into contact with the chemiluminescence substrate. Also, energy from the chemiluminescence having wavelengths falling within the visible light wavelength range, which chemiluminescence is produced by the labeling substance when the labeling substance is thus brought into contact with the chemiluminescence substrate, is stored on the stimulable phosphor contained in the stimulable phosphor layer of the stimulable phosphor sheet. Thereafter, the stimulable phosphor layer of the stimulable phosphor sheet, on which the chemiluminescence image information of the biopolymer has been stored, is then exposed to an electromagnetic wave acting as stimulating rays, which cause the stimulable phosphor to emit light in proportion to the amount of energy stored on the stimulable phosphor during its exposure to the chemiluminescence. The light emitted by the stimulable phosphor, upon stimulation thereof, is photoelectrically detected and converted into a digital image signal. The digital image signal is then processed and used for the reproduction of the chemiluminescence image information of the biopolymer as a visible image on a recording material. The chemiluminescence image detecting systems are disclosed in, for example, U.S. Pat. No. 5,028,793 and British Patent Publication GB No. 2,246,197A.
Furthermore, it has been proposed to use stimulable phosphors as electron beam detecting materials in electron microscope image detecting systems, the stimulable phosphors having the characteristics such that the stimulable phosphors absorb and store energy from an electron beam during exposure to the electron beam and, when the stimulable phosphors are then stimulated by an electromagnetic wave having wavelengths falling within a specific wavelength range, the stimulable phosphors emit light in proportion to the amount of energy stored on the stimulable phosphors during the exposure of the stimulable phosphors to the electron beam. Specifically, the electron beam is irradiated to a metal sample or a nonmetal sample, and an electron beam diffraction image or an electron beam transmission image of the sample is detected. The thus detected image is utilized for an element analysis, a sample composition analysis, a sample structure analysis, and the like. Alternatively, the electron beam is irradiated to an organism tissue, and an image of the organism tissue is detected.
Also, it has been proposed to use stimulable phosphors as radiation detecting materials in radiation diffraction image detecting systems, the stimulable phosphors having the characteristics such that the stimulable phosphors absorb and store energy from radiation during exposure to the radiation and, when the stimulable phosphors are then stimulated by an electromagnetic wave having wavelengths falling within a specific wavelength range, the stimulable phosphors emit light in proportion to the amount of energy stored on the stimulable phosphors during the exposure of the stimulable phosphors to the radiation. Specifically, with the radiation diffraction image detecting systems, the radiation is irradiated to a sample, and a radiation diffraction image of the sample is detected. The thus detected image is utilized for a sample structure analysis, and the like.
The electron microscope image detecting systems and the radiation diffraction image detecting systems described above are disclosed in, for example, Japanese Unexamined Patent Publication Nos. 59(1984)-15843 and 61(1986)-93538, and U.S. Pat. No. 4,889,990.
The aforesaid various systems utilizing the stimulable phosphor sheets as the image detecting materials have the advantages in that chemical processing, such as development processing, need not be performed as in cases where photographic film is used. Also, the aforesaid various systems utilizing the stimulable phosphor sheets as the image detecting materials have the advantages in that various kinds of image processing are capable of being performed on the obtained image signals, and desired visible images are capable of being reproduced from the processed image signals. Further, the aforesaid various systems utilizing the stimulable phosphor sheets as the image detecting materials have the advantages in that quantitative analyses are capable of being performed by use of computers.
Further, fluorescence image detecting systems utilizing fluorescent substances as labeling substances in lieu of radioactive labeling substances in the autoradiography image detecting systems have heretofore been known. With the fluorescence image detecting systems, analyses of gene sequences and gene expression levels, separation and identification of proteins, and evaluation of molecular weights and characteristics of proteins are capable of being performed in accordance with information obtained by reading out fluorescence images. Specifically, for example, after a fluoro chrome has been added to a liquid containing a plurality of DNA fragments to be subjected to electrophoresis, electrophoresis of the plurality of the DNA fragments may be performed on a gel support. Alternatively, electrophoresis of a plurality of DNA fragments may be performed on a gel support containing a fluoro chrome. As another alternative, after electrophoresis of a plurality of DNA fragments has been performed on a gel support, the DNA fragments having been subjected to the electrophores is maybe leveled with a fluoro chrome by, for example, a process for dipping the gel support in a liquid containing the fluoro chrome, the fluoro chrome may then be excited with excitation light to produce fluorescence, the thus produced fluorescence may be detected, and a fluorescence image may thereby be formed. In accordance with the thus formed fluorescence image, a DNA distribution on the gel support is capable of being detected.
As a further alternative, with the fluorescence image detecting systems, after electrophoresis of a plurality of DNA fragments has been performed on a gel support, the DNA fragments having been subjected to the electrophoresis may be denatured. Thereafter, at least part of the denatured DNA fragments may be transcribed to a transcription support, such as nitrocellulose, with a Southern blotting technique. The denatured DNA fragments and a probe having been prepared by labeling a DNA or an RNA, which is complementary to a target DNA, with a fluoro chrome, may then be subjected to hybridization. In this manner, only a DNA fragment, which is complementary to the probe DNA or the probe RNA, is selectively labeled with the fluoro chrome. Thereafter, the fluoro chrome, with which the DNA fragment described above has been labeled, may be excited with the excitation light to produce the fluorescence, the thus produced fluorescence may be detected, and a fluorescence image may thereby be formed. In accordance with the thus formed fluorescence image, a target DNA distribution on the transcription support is capable of being detected.
As a still further alternative, with the fluorescence image detecting systems, a DNA probe, which is complementary to a DNA containing a target gene and has been labeled with a labeling substance, may be prepared. The DNA probe and a DNA on a transcription support may then be subjected to hybridization. Also, an enzyme may be subjected to binding with the complementary DNA having been labeled with the labeling substance, and the thus bound enzyme may then be brought into contact with a fluorescence substrate in order to convert the fluorescence substrate into a fluorescent substance, which is capable of producing the fluorescence. Thereafter, the fluorescent substance may be excited with the excitation light to produce the fluorescence, the thus produced fluorescence may be detected, and a fluorescence image may thereby be formed. In accordance with the thus formed fluorescence image, a target DNA distribution on the transcription support is capable of being detected.
The fluorescence image detecting systems have the advantages in that a radioactive substance need not be used, and the gene sequences, and the like, are capable of being detected in a simple manner.
The autoradiography image detecting systems, the chemiluminescence image detecting systems, the electron microscope image detecting systems, the radiation diffraction image detecting systems, and the fluorescence image detecting systems described above are utilized for the same purposes of use. Therefore, there is a strong demand for an image read-out apparatus, which is capable of being utilized commonly for the autoradiography image detecting systems, the chemiluminescence image detecting systems, the electron microscope image detecting systems, the radiation diffraction image detecting systems, and the fluorescence image detecting systems described above.
Accordingly, there has been proposed an image read-out apparatus capable of being utilized commonly for the autoradiography image detecting systems, the chemiluminescence image detecting systems, the electron microscope image detecting systems, the radiation diffraction image detecting systems, and the fluorescence image detecting systems described above, in which the stimulable phosphor sheets are utilized.
The image read-out apparatus proposed for use in the systems described above comprises an optical head for irradiating the stimulating rays (or the excitation light) to the image carrier, such as the stimulable phosphor sheet provided with the stimulable phosphor layer, the transcription support containing the sample labeled with the fluorescent substance, or the gel support containing the sample labeled with the fluorescent substance, and collecting the light emitted by the image carrier, such as the light, which is emitted by the stimulable phosphor contained in the stimulable phosphor layer when the stimulable phosphor is stimulated by the stimulating rays, or the fluorescence, which is produced by the fluorescent substance for the labeling of the sample when the fluorescent substance is excited by the excitation light. In order to scan the image carrier, the optical head is capable of being moved in two dimensional directions along a plane parallel with the image carrier.
Both the stimulating rays for stimulating the stimulable phosphor and the excitation light for exciting the fluorescent substance will hereinbelow be referred to as the stimulating rays.
As the optical head described above, an optical head comprising a plane mirror and a convex lens has been proposed. With the proposed optical head, the stimulating rays are reflected by the plane mirror toward the image carrier, and the reflected stimulating rays are irradiated via the convex lens to the image carrier. Also, the light emitted by the image carrier is collected by the convex lens and is guided by the plane mirror toward a photodetector. Specifically, the convex lens plays both the role for converging the stimulating rays, which have been produced by a stimulating ray source and are irradiated to the image carrier, and the role for collecting the light emitted by the image carrier. The convex lens is located such that the position of a focal point of the convex lens coincides with the surface of the image carrier. The optical head is thus constituted such that the convex lens collimates the light emitted by the image carrier, and the collimated light impinges upon the plane mirror. Also, as the stimulating rays, ordinarily, a laser beam having a small beam diameter is utilized. The laser beam has good converging characteristics. However, in order for an image having a high sharpness to be obtained, it is desired that the position of a beam waist of the stimulating rays coincides with the position of the surface of the image carrier. However, the position of the beam waist of the stimulating rays does not necessarily coincide with the position of the focal point of the convex lens, and therefore it often occurs that the position of the beam waist of the stimulating rays is located on the side spaced away from the surface of the image carrier toward the convex lens. In such cases, if the position of the beam waist of the stimulating rays and the position of the surface of the image carrier are set to be close to each other, the position of the focal point of the convex lens will be shifted from the position of the surface of the image carrier to a position on the side opposite to the convex lens. In cases where the position of the focal point of the convex lens is thus shifted, the light emitted by the image carrier cannot be collimated by the convex lens, and therefore the light emitted by the image carrier impinges in a divergent state upon the plane mirror. In such cases, the light emitted by the image carrier cannot be sufficiently collected and guided to the photodetector, and therefore the sensitivity of the image read-out apparatus cannot be kept high.